1. Field of the Invention
The present invention relates to a seatback spring device.
2. Description of the Prior Art
In a conventional seatback spring device, which has been disclosed in U.S. Pat. No. 4,697,848 for example, three laterally spaced S-shaped springs are arranged within a frame and are secured thereto.
However, this device does not fit to the curvature of the back of the occupant because the back is divided into two portions, one is supported by the springs and the other is not so.